Folding chairs are collapsible or foldable for ease of storage and transportation. Folding chairs with pivoting legs are often desirable because they generally resemble the configuration and structure of unfoldable chairs and save on storage space. However, folding chairs can lack some of the stability of unfoldable chairs, due at least in part to the foldable nature of the chairs and the generally lightweight construction used for ease of portability.
U.S. Pat. No. 3,199,915 entitled "Folding Chair" and U.S. Pat. No. 2,860,692 entitled "Chair" disclose foldable chairs having legs which in operating position are perpendicular to the seat at each of the four comers of the seat in operating position. Each of the front legs is connected to the seat support which is pivotably connected to the back member of the chair. This pivotable connection at the underside of the seat and back member junction allows for pivoting of the front legs about an axis to permit the legs to be positioned substantially co-planar to the back member. The '915 patent also discloses a mechanism to secure the seat in its operating position.
The general configuration of conventional folding chairs with pivoting legs, particularly in view of its need for light-weight construction, offers little stability to a person who is not appropriately centered on the seat, since the forces pressing down on the seat are not supported equally by the legs at the four corners. Therefore, someone sitting at the front edge of the seat may tip the chair forward. Likewise, someone leaning too heavily against the back of the chair can tilt it in the other direction. This may also be the case in a situation where someone stands on a chair, for example to reach something on a high shelf.
U.S. Pat. No. 250,343 entitled "Folding Chair" discloses a foldable chair having braces at each of the front legs and two rundles extending between each front leg and the back member. This design provides some added stability in comparison to the foldable chair without these supports, however it requires the numerous additional parts of braces and rundles to accomplish the goal, which add to the cost and weight of the chair.